1. Field of the Invention
The present invention relates to a method, an apparatus, and a program for processing a three-dimensional image.
2. Description of the Related Art
In a known method, a contact-type position sensor is used as an image processing apparatus for inputting three-dimensional information of an actually present object (such as a shape and a surface attribute). In this method, a probe is put into contact with each point of the object, three-dimensional coordinates of the probe are detected by the position sensor, and the three-dimensional coordinates of each point of the object are input.
Since this method of using the contact-type position sensor requires that the probe be put into contact with the points of the object, there is some limitation. For example, the object to be detected must have a certain degree of solidity and it takes some time to measure the coordinates.
On the other hand, non-contact-type three-dimensional measurement devices are also known. Because of its high-speed measurement capability, the non-contact-type measurement device is used to input data in a CG (Computer Graphics) system or a CAD (Computer-Aided Design) system, to measure the human body, or to recognize objects visually in a robot system.
A slit-ray projection method (or “light chopping” method) or a pattern projection method is known as a non-contact three-dimensional measurement method. These methods are active measurement techniques in which a projector for projecting a particular reference beam to a target object to be measured, and a photosensitive sensor for receiving a beam reflected from the target object are used to obtain three-dimensional data from calculation based on trigonometry.
In the slit-ray projection method, a slit ray is projected and deflected to scan the target object. In the pattern projection method, a plurality of two-dimensional patterns are successively directed to the target object. The resulting three-dimensional data is represented as data points, namely, a set of pixels representing three-dimensional positions of a plurality of regions on the target.
Such a three-dimensional measurement apparatus occasionally has a function of acquiring a surface attribute to obtain texture information of the target object, besides a function of obtaining the three-dimensional data of the target object.
Conventional three-dimensional measurement apparatuses have the function of acquiring texture information of the surface of the object but no function of acquiring data relating to the surface feature or glossiness of the object. When the three-dimensional image is reproduced, the effect of illumination light projected to the object is not accounted for, and an unnatural-looking three-dimensional image results. When the three-dimensional image is reconstructed, the shape, the effect of the position and the color of a light source may need to be changed in a particular image capturing environment. In practice, however, this is not done in any way, and the resulting image becomes much different in appearance from the object. The conventional three-dimensional measurement apparatus is unable to convey glossiness or other surface features of the object.